- Hotsearch Water Filter| Water Purifier| Water Dispenser| Garden Products|
[Article Title]Ultrafiltration as a whole-house machine
[Artical Suimmary] Water quality, scarcity issues bring a technology to the fore.
[Article Contect]
Over the last five years, we have seen greatly increased concern over the biological contaminants in drinking water ?both from the threats of bioterrorism and from recent natural disasters such as Hurricane Katrina. Other concerns include widely reported deaths and illnesses caused by E. coli, Cryptosporidium and other waterborne pathogens.
Environmental groups, public safety organizations and regulatory agencies also have become concerned with the hazards posed by disinfection byproducts and other unwanted chemicals in the water supply that can be reduced or eliminated with the addition of an inline granulated activated carbon (GAC) cartridge. Today more than half of all new homes in the US and Canada are being built in areas without municipal water and sewage infrastructure, leaving them especially vulnerable to biological contamination from source groundwater and surface water used for drinking. Increasingly common breaks in municipal water delivery lines raise the possibility of contamination of centrally treated water as it travels to homes. Ultrafiltration is a constant-flow point-of-entry (POE) technology that arrests impurities as small as 0.02 microns, including 99.99 percent of bacteria and cysts, plus 99.95 percent of viruses. POE technology Systems range in cost from $2,700 to $5,000 depending on size and supplemental carbon filtration for taste and odor. Ultrafiltration treats biologically contaminated water originating from wells, surface water and often-compromised municipal delivery systems ?using no chemicals or maintenance-intensive devices, except where backup protection is chosen. Minimal pressure drop Like RO systems, ultrafiltration works on available water pressure and requires no electricity to deliver high-quality drinking water. The technology is the same as with industrial-grade membranes, proven in water treatment plants worldwide. Unlike the flat membranes used in reverse osmosis, some hollow-fiber membranes resemble strands of spaghetti that are hollow inside (see sidebar, "Two types of hollow-fiber UF membranes"). Others are strands with capillaries in every fiber, which can make them stronger and more efficient at dealing with impurities trapped on the surfaces of the walls. The multi-bore walls of the membrane strands have billions of pores that filter out particles, turbidity and pathogens, while allowing water to flow through with minimal pressure drop. Ultrafiltration membranes filter down to approximately 0.20-0.10 microns nominal. The nominal pore size is the primary determinant of the particle/pathogen rejection characteristics of the membrane. For UF membranes to be capable of bacteria and virus rejection, the membrane pore distribution must be very tight. Achieving a flow rate Surface area is another key factor in membrane performance and represents the amount of available membrane area for water to pass through. A generous surface area, combined with higher permeability, will result in larger water output, necessary to satisfy total household needs, without requiring a holding tank. No undersink storage tanks are required because these are flow-through systems. Hollow fiber ultrafiltration is highly efficient (97 to 98 percent) compared with typical RO systems. Water efficiency A meter/controller determines when to flush the module and how much water to use in the process. Microprocessor technology in these systems can initiate flushing, only as needed. A flush cycle is triggered only when a preset number of gallons pass though the membrane filter. Frequency and duration of the flush setting will depend on the quality of the incoming water. A controller can also sense when water has not been used in a 24-hour period and will initiate a brief maintenance flush that keeps the system fresh while using minimal water. System status can be indicated by LED lights. Rural areas benefit It can be a cost-effective substitute for utility-delivered water in small communities. In emergency situations with boil orders in effect, HF UF will make a steady supply of biologically safe drinking water for drinking, bathing, showering and household use. For the individual home, it can produce up to 10 gallons per minute on a continuous basis. That may even be enough for small apartment buildings. Some systems can be installed to function even during power interruptions. Ultrafiltration components For reducing organic chemicals including chlorine and its byproducts, an optional GAC carbon post-filter is recommended. The system should be installed near the water meter (if municipal water), or near the pressure tank if the source is well water. Outside hose bibs should not be connected to the filter system. One-inch fittings would be typical and should meet most plumbing codes. UF system maintenance The unit should be sanitized at least annually with chlorine bleach. Quantity issues and quality As water becomes scarcer in many states, the quality decreases proportionately. Ultrafiltration provides biologically safe water to every tap in the home, without wasting water. That抯 a plentiful supply of healthy water, coming from a 揼reen?whole-house system.
